Chapter 1. Introduction

LandSerf allows you to visualise and perform analysis on spatial data. It is primarily designed to be used with surface and elevation models, but will work with most types of 'GIS' data. It currently supports raster DEM and vector TIN, contour and metric surface network models of elevation. What makes the software unique, is the ability to perform surface analysis over a range of scales, and characterise any scale dependent behaviour.

1.1 Starting LandSerf

Depending on your operating system, you can start LandSerf in a number of ways:

Platform	Start menu	Screen icon	Command line
Windows (95/98/NT/2000/XP)	Yes	Yes (double-click icon on desktop)	Yes (LandSerf.bat)
Linux	No	No	Yes (landserf.sh)
MacOS	No	Yes (double-click the LandSerf icon in the Applications folder)	Yes (landserf.sh)

By starting from the command line, various command line parameters can also be provided that will start LandSerf with raster and/or vector files preloaded. The options are given below, where names in <triangular_brackets> should be substituted with an appropriate file name and the | symbol indicates alternative options.

Command line parameter	Explanation
surface|primary <raster_file>|<vector_file>	Starts with the given file loaded as a primary object.
drape|secondary <raster_file>|<vector_file>	Starts with the given file loaded as a secondary object.
raster <raster_file>	Starts with the given file loaded as an unselected raster.
vector <vector_file>	Starts with the given file loaded as an unselected vector map.
display raster|relief|clear|vector	Starts with the given display type.
experimental true|false	Enables or disables extra experimental functionality (used for testing). By default experimental functionality is turned off.
Examples:
LandSerf primary c:\data\mountains.srf secondary "c:\My Images\photo.jpg" display relief
	Start LandSerf (in Windows) with the file mountains.srf displayed as a shaded relief map with the image photo.jpg draped over it.
./landserf.sh vector ~/data/coast.vec primary ~data/landuse.shp display vector
	Start LandSerf (in Unix) with the files coast.vec and landuse.shp pre-loaded, with the second of these displayed.

1.2 Using LandSerf

The software is largely controlled via a series of menus or buttons that either perform actions or open further dialogue boxes. Graphics appear in the main area of the window, while 'thumbnail' images of all loaded data appear in the left-hand area. The status of the system is reported at the bottom of the window. The entire window can be resized at any stage with all graphics being rescaled accordingly.

For processing that is likely to take some time, a 'percentage complete' bar is displayed in the bottom right-hand corner. Any process can be stopped by clicking on this bar.

LandSerf's initial screen.

Note: New to Version 2.2 is the ability of MacOS X users to select the native 'Aqua' look and feel. The arrangement of the main windows is identical, but the menu is placed at the top of the screen in common with other MacOS X applications.

LandSerf can store any number of raster or vector objects, limited only be the memory of the local system. Much of the raster analysis and display is applied to the current primary raster and possibly a secondary raster. To select a primary raster, click on the relevant thumbnail with the left mouse button. A primary raster will then be indicated by the black border around the thumbnail image. Secondary raster selection can be made by clicking on a thumbnail with the right menu button or with the left button while holding down the shift key. Note that the order of thumbnails does not determine their primary/secondary status.

The same selection rules apply to vector maps. Primary vectors are selected with the left mouse button, secondary with the right (or mouse button with the shift key held down). Thumbnail images of vector maps can be distinguished by the 'V' symbol in the top-left corner.

The range of visualisation and analysis options available will depend on the number and type of spatial objects that have been been selected.

Spatial object selection.

1.3 Console Output

LandSerf keeps a record of all options chosen by the user as well as any messages displayed in the status bar at the bottom of the screen. This can be useful if you wish to recall a sequence of operations previously undertaken. The record is stored in a file called landserfLog.txt in the main LandSerf directory. This file is reset every time a new session is started. Additionally, the logging output is echoed to the LandSerf console (see figure below), which can be viewed at any time by selecting the Help->Show console menu option.

LandSerf console output.

Any errors that stop LandSerf from working correctly are also reported to the console/log file. If these errors appear to be a bug with the program, please report them to jwo@landserf.org attaching the landserfLog.txt file that reports the error.

1.4 Functionality

The following features are currently available in LandSerf. Users of the previous version may also wish to view the changes since the previous release.

Input/Output.

• Raster and vector import in a range of 28 GIS and other formats - LandSerf's own (platform independent) raster, vector and 3d file formats; ArcGIS rasters and vectors (ASCII grid, binary images, 'generate' vectors, shapefiles); EDX ASCII DEMs; GRASS vectors and rasters (text only); Global Hierarchical Shoreline vectors; visualisation software VistaPro (ASCII and binary); Virtual Terrain Project 'BT files'; Terragen (terrain and binary formats); Ordnance Survey NTF DEMs and vectors (NTF 2.0); Ordnance Survey MasterMap vector maps (compressed and uncompressed); generic (ASCII and binary) rasters, vectors and point files; image files (GIF, JPEG, PNG, TIFF and GeoTIFF file formats); USGS native DEM files; GTOPO30 files and SRTM/SRTM30Plus global DEMs.
• Raster and vector export in a range of 21 GIS and other formats - LandSerf's own (platform independent) raster, vector formats; ArcGIS rasters and vectors (ASCII grid, binary images, 'gridFloat' and 'generate' files); generic (ASCII and binary) rasters, vectors and point files; GRASS GIS (ASCII only); image files (GIF, JPEG, PNG, BMP); Scalable vector graphics (SVG); 3d vector flythroughs over elevation models; visualisation software VistaPro (ASCII and binary); Terragen (binary and .ter formats); VRML virtual worlds (compressed and uncompressed);
• LandSerf files can be printed directly. Output includes the current raster image and vector overlay, titles, bounds and supplementary notes.
• If you have a Garmin GPS receiver and serial cable, you can import Waypoints, Routes and Tracks directly from the unit. Vector objects in LandSerf can be exported to the GPS receiver as waypoints.

Editing Functionality.

• Raster title and supplementary notes.
• Raster boundary positions and resolution including interactive subsetting and reinterpolation.
• Raster layer combination.
• Vector map title, boundary positions and supplementary notes.
• On-screen digitizing of vector maps.
• Map projection information (projection type and ellipsoid)
• Colour tables including selection from preset palettes.
• Editing of multiple attributes in an attribute table.

Display Functionality.

• Interpolated 'k-colour' raster.
• Shaded relief with variable blending with 'k-colour' rasters.
• Interactive zooming and panning
• Coloured vector overlay.
• Vector map labelling
• Blended primary and secondary raster images.
• Hue-Saturation images (primary raster representing saturation, secondary representing hue).
• 3D perspective views with interactive 'flythrough' navigation.

Surface Query.

• Raster information - title, bounding area, min/max values, colour table, raster type, supplementary notes.
• Vector information - title, bounding area, min/max values, colour table, supplementary notes.
• Interactive query of raster values, reported as (x,y,z) triplets.
• Interactive generation of surface profiles
• Interactive query of changing surface parameters/features with scale, reported as a parameter-scale graph.
• Statistical summary of raster data (measures of average, dispersion, spatial autocorrelation and fractal dimension).
• Scatterplot of surface and drape values.
• Log-log variogram of raster values.
• Frequency histogram of surface values.
• 'Hammock Plot' of surface values (detects interpolation artifacts).

Surface Transformation.

• Vector to raster conversion.
• DEM to TIN and TIN to DEM conversion.
• Delaunay triangulation of points.
• Contour threading of DEMs.
• Removal of voids from raster maps
• Raster value transformations (scaling, translation etc.) including generation of null values
• Interactive rectification of rasters with RMSE error reports.
• Projection between lat/long, UTM, OSGB and Swiss National Grid coordinate systems .

Surface Analysis.

• Calculation of elevation, slope, aspect, 7 measures of curvature, and feature type at any scale.
• Average and variation of any surface parameter/feature over a range of window scales.
• Surface feature network derivation (creates linear networks of ridges and channels bounded by pits, passes and peaks).
• Peak detection using relative drop methods.
• Pit removal from surfaces.
• Fuzzy feature classification.

LandSerf Configuration.

• User defined selection of analysis scale and distance decay parameters.
• User defined selection of feature extraction tolerances.
• Shaded relief parameter settings (sun elevation and azimuth, reflectance properties etc.)